Glass components produced via reforming of initial material parts, such as glass sheets, have many applications, a significant one being glazing for the automotive industry. Reformed glass sheets are also used in display applications, for example in producing liquid crystal displays (LCDs), electrophoretic displays (EPD), organic light emitting diode displays (OLEDs), plasma display panels (PDPs), or the like.
Prior to reforming, glass sheets are commonly fabricated by flowing molten glass to a forming body whereby a glass ribbon may be formed by a variety of ribbon forming process techniques, for example, slot draw, float, down-draw, fusion down-draw, or up-draw. The glass ribbon may then be subsequently divided to provide sheet glass suitable for further processing into a desired intermediate of a final product. Recently there has been a growing interest in extremely high quality thin glass sheets that are reformed into more complex three dimensional shapes, such as a combination of flat portions and locally highly curved shapes.
The common processes used to reform glass sheets often involve a heating step at temperatures where deformation occurs under gravity or under mechanical actuation. Heating of a glass sheet using conventional techniques involves application of heat to the whole surface of the glass sheet. For example, known means for achieving heating of a glass sheet for reforming include the use of metal-based wires wound around a ceramic support. However, such techniques have not heretofore been satisfactory because heating of the entire glass sheet is not necessarily a desirable result, especially in a reforming operation where only local deformations are needed and heating of other portions of the glass sheet could result in damage and/or degradation of physical, optical and/or electrical characteristics.
There are known means to achieve the heating of glass sheets in furnaces, such as the use of electrically conductive ceramic materials, the most common being silicon carbide and disilicide molybdenum. The silicon carbide and/or disilicide molybdenum materials are generally shaped as straight or curved tubes for furnace applications. These types of heating elements are used to dissipate power via heat radiation into the furnace environment. Although the use of such electrically conductive ceramics to heat furnaces is well known in the glass industry, there has been no development or application of such techniques to heat a specific, localized area on a glass sheet as would be desirable in a reforming process.
Thus, there are needs for methods and apparatus for localized heating of glass sheets while retaining a high level of flatness in desired areas of a glass sheet; retaining pristine aspects of the glass sheet; obtaining a desired amount of deformation in certain areas of interest; and maintaining a high level of dimensional control. Such process and apparatus can be suitable for reforming glass sheets in a wide range of applications, such as display applications.